1. Field
Devices consistent with exemplary embodiments relate to a wireless communication device, and more particularly, to a wireless communication device having a constant antenna performance even if the device is bent or is folded.
2. Description of the Related Art
Various types of mobile communication terminal devices, such as a flip type, a folder type, and a slide type, have been developed. Recently, a tablet type mobile communication terminal device having a touch screen provided on a front portion thereof has also been developed. Since such a device, also referred to as a tablet phone, includes a display with a full touch screen provided on the front portion thereof, the tablet phone has the advantages that its input and output are more intuitive, and fine designs can be implemented. Further, since the recently developed tablet phone has a minimum housing thickness through SOC designs, portability of the tablet phone can be maximized.
Hereinafter, it is expected that a mobile communication terminal device will evolve into a flexible phone that can be bent or folded. A flexible phone is classified into a watch phone, a foldable phone, and a bendable phone. The watch phone is a phone that can be worn on the wrist of a user in the form of a watch, and commercialization of a smart watch is expected in the course of time. The foldable phone is a phone having a plurality of folded bodies, and can be folded in various shapes depending on the intended use or purpose thereof. The bendable phone is a phone of which the body can be bent, and corresponds to a device generally referred to as a flexible phone. The flexible phone may be configured in two states: a wearing state in which the flexible phone is worn and a shape of the flexible phone is changed and a release state in which the flexible phone is not worn. FIG. 1A illustrates a bendable phone 10 in a wearing state, and FIG. 1B illustrates a watch phone 20.
However, it has been found that the shape change of the flexible phone may exert an influence on the performance of an antenna. That is, it has been found that an additional mode occurs due to coupling in a flexible phone that is bent or folded.
FIG. 2 is a conceptual view illustrating a coupling phenomenon of a flexible phone that is in a bent state.
The transmission and reception performance of an antenna depends on a combination of an emitter and ground. As shown in FIG. 2, if a flexible phone 10 is bent and if an antenna 11 approaches an opposite ground 13 of the flexible phone 10, additional resonance or impedance change occurs in the antenna transmission and reception signal. That is, signal energy that is emitted from the antenna 11 is excited to a system ground 13 that forms a part of the antenna, and this excited signal energy causes the characteristic change of the antenna. In other words, a kind of feedback loop is formed between the antenna 11 and the ground 13, and this phenomenon is called an additional mode due to the coupling. If the additional mode due to the coupling occurs, the antenna transmission and reception performance is lowered in comparison to the antenna transmission and reception performance in the case where the flexible phone 10 is not bent.
FIG. 3 is a graph illustrating the result of a measurement of a frequency change in a state where a flexible phone is bent.
As illustrated in FIG. 3, if the flexible phone is bent (“A” state), it can be seen that the operating frequency is lowered to approximately 1.6 GHz. This lowering of operating frequency indicates that a deviation of about 300 MHz is occurring as compared with the operating frequency in the state where the flexible phone is not bent (“B” state). Further, if the flexible phone is bent, it can be seen that the bandwidth of the operating frequency is greatly reduced. Accordingly, in the case where the flexible phone is bent, the antenna performance becomes deteriorated. If the shape of the flexible phone is changed, the frequency characteristics thereof differ depending on the changed shape, and thus it may be difficult to expect a consistent antenna performance.
Accordingly, there is a need for a technology of a wireless communication device that has a relatively consistent antenna performance even if the shape of the terminal device is changed.